- How is hepatitis C diagnosed?
- What are the lab tests for hepatitis C?
- What are the stages of hepatitis C?
- Once HCV infection is staged, what other lab tests might be recommended?
- Are home HCV tests available?
- What is the Hepatitis C Lookback Program?
How is hepatitis C diagnosed? Top of Page
HCV is diagnosed through laboratory-based tests. Some tests detect the presence of HCV antibodies, elevated liver enzymes and the virus itself in the bloodstream. Others assess the amount of cell damage the virus has caused to the liver.
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What are the lab tests for hepatitis C?
The available tests for detecting HCV fall into six categories:
A blood test that indicates if liver enzyme levels are elevated. This is often the first clue to possible liver disease. Elevated liver enzymes indicate that there is inflammation in the liver. The enzymes are released into the bloodstream when a liver cell is damaged, becomes ruptured and dies. But levels don't give you solid information about the cause of degree of the damage. In fact, determining enzyme levels at any one point in time is not as important as tracking large swings in enzyme levels over time.
ELISA II blood test that looks for the presence of antibodies to the virus. If the results come back positive for HCV, physicians confirm the finding with a PCR test. This is necessary because ELISA II can determine that exposure to HCV happened but it cannot confirm if the infection is current or occurred in the past and is now eliminated from the body.
Viral Load Tests Viral load tests, including a PCR (polymerase chain reaction) and branched-chain DNA assay are tests for hepatitis C that are best for patients with unexplained liver disease. The PCR is an ultra-sensitive test that measures the viral load in your bloodstream by targeting the RNA within the virus. A PCR test is read as positive or negative and does not usually quantify the amount of virus. The test, however, will determine if the virus is active and multiplying in the bloodstream.
Hepatitis C RNA by branched-chain DNA (bDNA) assay is a test developed by Chiron Corp. to measure the quantity of hepatitis C virus in the blood. The level of virus may correlate with the chance of response to interferon.
A blood test to determine exactly which genotype of the HCV virus you have. Because various genotypes react differently to medications, knowing your genotype allows the doctor to determine the optimal length of treatment with combination therpay of interferon and ribavirin. (HCV subtypes 1a and 1b are relatively resistant to interferon and to combination therapy. Subtypes 2 and 3 are much more likely to respond positively.
Imaging tests such as a CT scan or ultrasound. These tests are used to get a clearer picture of your liver's size, any structural changes that might have happened as a result of inflammation and the condition of the portal vein and hepatic artery. The CT scan can also be used to identify early liver tumors. People with cirrhosis may rely on a series of ultrasound tests instead of repeated X-rays to determine if liver cancer is developing.
A liver biopsy to discover the degree of liver damage and the stage of the disease. A biopsy removes a small amount of liver tissue-usually less than 1/5,000th of the liver. The tissue is then examined under a microscope to see what cell damage, or cirrhosis, has occurred. Although the results are generally accurate, about 5 % of the time, the biopsy underestimates the amount of inflammation or scar tissue, and less than 1% of time it leads to an overestimation of damage.
In addition to showing development of cirrhosis, a biopsy can:
- clarify other tests results that may not be conclusive
- alert the doctor of the need to begin treatment (if cirrhosis is discovered)
- determine if the person has any liver disease resulting from medications
- assist the doctor in establishing a cancer screening schedule if cirrhosis is revealed.
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What are the stages of hepatitis C? Top of Page
Doctors can determine the stage of your HCV infection once they have the results of your liver biopsy. Identifying the stage helps determine treatment options but doesn't reveal much about how long you've thad HCV or how long until you progress to the next stage. The timeline is quite particular and unpredictable for each individual
Stage 1 indicates minimal scarring of the liver. This stage used to be called Chronic Persistent Hepatitis C or Mild Chronic Active Hepatitis C
Stage II means that scarring has developed and extends outside the portal tracts--the areas in the liver that house the blood vessels and are the first areas affected by liver inflammation.
Stage III means that the fibrosis is spreading or bridging out slightly to adjacent portal tracts.
Stage IV means that the fibrosis has progressed into cirrhosis and advanced scarring of the liver tissue. Often simply referred to as cirrhosis, in this stage many of the complications associated with HCV develop.
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Once HCV infection is staged, what other lab tests might be recommended?
Once your doctor has diagnosed the stage of HCV infection, he/she will monitor you for development of complications using several blood tests that pinpoint changes in your liver function, including:
- A test for bilirubin levels, the substance that triggers jaundice. Rising levels indicate that the liver is no longer able to process this naturally occuring by-product of red blood cells' life cycle;
- A test for alkaline phosphatase (similar to the GGT or gamma-glutamyl transferase test) that measures liver enzyme levels and indicates liver inflammation and damage;
- A test for serum albumin that can reveal if the liver's ability to manufacture or process vital nutrients is deteriorating or if a person's nutritional habits are poor;
- A test for clotting factors that checks prothrombin (PT) time and levels, and evaluates the overall clotting function of at least five clotting factors.
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Are home HCV tests available? Top of Page
The Food and Drug Administration approved an at-home HCV test in Spring 1999 called "Home Access Hepatitis C Check Test Service." It helps people determine if they have been exposed to the virus and offers counseling and referral to appropriate medical care. The blood test is sent to a lab, and four to five days after receiving the sample, the lab reports the results. For information on the test call 1-888-888-HEPC or visit their web site at www.homeaccess.com.
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What is the Hepatitis C Lookback Program? Top of Page
This is a program initiated by the federal government through which hundreds of thousands of people receive letters from blood banks and hospitals informing them that they may have been exposed to hepatitis C during blood transfusions prior to 1992. For people without access to free tests or a test covered by insurance, the $69.95 HCV test (see above) may offer an easy way to determine if one has been infected by HCV. (6)
Reference: Cohen, M., Gish, R. Doner, K, "The Hepatitis C Help Book." St. Martin's Press. 2000.
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